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Urine Test

Test Overview

A urine
test checks different components of urine, a waste product made by the
kidneys. A regular urine test may be done to help find
the cause of symptoms. The test can give information about your health and
problems you may have.

The
kidneys take out waste material, minerals, fluids, and
other substances from the blood to be passed in the urine. Urine has hundreds
of different body wastes. What you eat and drink, how much you exercise, and how
well your kidneys work can affect what is in your urine.

More than
100 different tests can be done on urine. A regular
urinalysis often includes the following tests:

Color. Many things affect urine color, including
fluid balance, diet, medicines, and diseases. How dark or light the color is
tells you how much water is in it. Vitamin B supplements can turn urine bright
yellow. Some medicines, blackberries, beets, rhubarb, or blood in the urine can
turn urine red-brown.

Odor. Urine does not smell very strong, but it has a
slightly "nutty" odor. Some diseases cause a change in the odor of urine. For
example, an infection with E. coli bacteria can cause a
bad odor, while
diabetes or starvation can cause a sweet, fruity
odor.

Specific gravity. This checks the amount of
substances in the urine. It also shows how well the kidneys balance the amount
of water in urine. The higher the specific gravity, the more solid material is
in the urine. When you drink a lot of fluid, your kidneys make urine with a
high amount of water in it, which has a low specific gravity. When you do not
drink fluids, your kidneys make urine with a small amount of water in it, which
has a high specific gravity.

pH. The
pH is a measure of how acidic or alkaline (basic) the
urine is. A urine pH of 4 is strongly acidic, 7 is neutral (neither acidic nor
alkaline), and 9 is strongly alkaline. Sometimes the pH of urine is affected by
certain treatments. For example, your doctor may instruct you how to keep your
urine either acidic or alkaline to prevent some types of
kidney stones from forming.

Protein. Protein normally isn't found in the
urine. Fever, hard exercise, pregnancy, and some diseases, especially kidney
disease, may cause protein to be in the urine.

Glucose. Glucose is the type of sugar found in
blood. Normally there is very little or no glucose in urine. When the blood
sugar level is very high, as in uncontrolled diabetes, the sugar spills over
into the urine. Glucose can also be found in urine when the kidneys are damaged
or diseased.

Nitrites. Bacteria that cause a
urinary tract infection (UTI) make an enzyme that
changes urinary nitrates to nitrites. Nitrites in urine show a UTI is
present.

Ketones. When fat is broken down for energy, the
body makes substances called ketones (or ketone bodies). These are passed in
the urine. Large amounts of ketones in the urine may mean a very serious
condition,
diabetic ketoacidosis, is present. A diet low in
sugars and starches (carbohydrates), starvation, or severe vomiting may also
cause ketones to be in the urine.

Microscopic analysis. In this test, urine is spun
in a special machine (centrifuge) so the solid materials (sediment) settle at
the bottom. The sediment is spread on a slide and looked at under a microscope.
Things that may be seen on the slide include:

Red or white blood cells. Blood cells aren't found in urine normally. Inflammation,
disease, or injury to the kidneys, ureters, bladder, or urethra can cause blood
in urine. Strenuous exercise, such as running a marathon, can also cause blood
in the urine. White blood cells may be a sign of infection or kidney
disease.

Casts. Some types of kidney disease
can cause plugs of material (called casts) to form in tiny tubes in the
kidneys. The casts then get flushed out in the urine. Casts can be made of red
or white blood cells, waxy or fatty substances, or protein. The type of cast in
the urine can help show what type of kidney disease may be
present.

Crystals. Healthy people often have
only a few crystals in their urine. A large number of crystals, or certain
types of crystals, may mean kidney stones are present or there is a problem
with how the body is using food (metabolism).

Bacteria, yeast cells, or parasites. There are no bacteria, yeast cells, or
parasites in urine normally. If these are present, it
can mean you have an infection.

Squamous cells. The
presence of
squamous cells may mean that the sample is not as pure
as it needs to be. These cells do not mean there is a medical problem, but your
doctor may ask that you give another urine sample.

Why It Is Done

A urine test may be done:

To check for a disease or infection of the
urinary tract. Symptoms of a urine infection may
include colored or bad-smelling urine, pain when urinating, finding it hard to urinate,
flank pain, blood in the urine (hematuria), or fever.

To check the
treatment of conditions such as diabetes, kidney stones, a urinary tract
infection (UTI), high blood pressure (hypertension),
or some kidney or liver diseases.

As part of a regular physical examination.

How To Prepare

Do not eat foods that can color the
urine, such as blackberries, beets, and rhubarb, before the test. Do not
exercise strenuously before the test.

Tell your doctor if you are menstruating or close to starting your menstrual
period. Your doctor may want to wait to do the test.

Your doctor may ask
you to stop taking certain medicines that color the urine. These include
vitamin B, phenazopyridine (Pyridium), rifampin, and phenytoin (Dilantin). Be
sure to tell your doctor if you are taking
diuretics, which may affect the test results.

Talk to your doctor any concerns you have regarding
the need for the test, its risks, how it will be done, or what the results will
mean. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).

How It Is Done

A routine urine test can be done in your
doctor's office, clinic, or lab. You may also be asked to collect
a urine sample at home and bring it with you to the office or lab for
testing.

Collecting a urine sample from a small child or baby is done by using a special plastic bag with tape around
its opening. The bag is placed around the child's genitals until he or she urinates. Then you carefully remove
the bag. To collect a urine sample from a very sick baby, a doctor may use a urinary catheter through the
urethra or a needle through the baby's belly directly into the bladder (suprapubic tap).

Clean-catch midstream one-time urine collection

Wash your hands to make sure they are clean
before collecting the urine.

If the collection cup has a lid,
remove it carefully and set it down with the inner surface up. Do not touch the
inside of the cup with your fingers.

Clean the area around your
genitals.

A man should retract the foreskin, if
present, and clean the head of his penis with medicated towelettes or
swabs.

A woman should spread open the genital folds of skin with
one hand. Then she can use her other hand to clean the area around the
urethra with medicated towelettes or swabs. She should
wipe the area from front to back so bacteria from the
anus is not wiped across the urethra.

Begin urinating into the toilet or urinal. A
woman should hold apart the genital folds of skin while she
urinates.

After the urine has flowed for several seconds, place the
collection cup into the urine stream and collect about
2 fl oz (60 mL) of this
"midstream" urine without stopping your flow of urine.

Do not
touch the rim of the cup to your genital area. Do not get toilet paper, pubic
hair, stool (feces), menstrual blood, or anything else in the urine
sample.

Finish urinating into the toilet or
urinal.

Carefully replace and tighten the lid on the cup, and then
return it to the lab. If you are collecting the urine at home and cannot get it
to the lab in an hour, refrigerate it.

Double-voided urine sample collection

This method
collects the urine your body is making right now.

Urinate into the toilet or urinal. Do not
collect any of this urine.

Drink a large glass of water, and wait
about 30 to 40 minutes.

Then get a urine sample. Follow the
instructions above for collecting a clean-catch urine sample.

Return the urine sample to the lab. If you are
collecting the urine at home and cannot get it to the lab in an hour,
refrigerate it.

24-hour urine collection

Your doctor may ask you to collect your urine for 24 hours.

The collection period usually starts in the
morning. When you first get up, urinate—but don't save this urine. Write down
the time that you urinated to mark the beginning of your 24-hour collection
period.

For the next 24 hours, collect all your urine. Your doctor
will usually provide you with a large container that holds about
1 gal (4 L) and has a small
amount of preservative in it. Urinate into a smaller, clean container, and then
pour the urine into the large container. Avoid touching the inside of the
container with your fingers.

Keep the large container in the
refrigerator during the collection period.

Urinate for the final
time at or just before the end of the 24-hour period. Add this urine to the
large container, and write down the time.

How It Feels

Risks

There is no chance for problems in collecting a urine sample.

Results

A urine test checks different components
of urine, a waste product made by the
kidneys.

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Urine test results

Color

Normal: Pale
to dark yellow

Abnormal: Many foods and
medicines can affect the color of the urine. Urine with no color may be caused
by long-term kidney disease or uncontrolled
diabetes. Dark yellow urine can be caused by
dehydration. Red urine can be caused by blood in the
urine.

Abnormal: Some foods (such
as asparagus), vitamins, and antibiotics (such as penicillin) can cause urine
to have a different odor. A sweet, fruity odor may be caused by uncontrolled
diabetes. A
urinary tract infection (UTI) can cause a bad odor.
Urine that smells like maple syrup can mean maple syrup urine disease, when the
body can't break down certain
amino acids.

Abnormal: A very high
specific gravity means very concentrated urine, which may be caused by not
drinking enough fluid, loss of too much fluid (excessive vomiting, sweating, or
diarrhea), or substances (such as sugar or protein) in the urine. Very low
specific gravity means dilute urine, which may be caused by drinking too much
fluid, severe kidney disease, or the use of
diuretics.

A one-time urine collection, if normal, will be negative for glucose.1

Abnormal:Intravenous (IV) fluids can cause glucose to be in the
urine. Too much glucose in the urine may be caused by uncontrolled diabetes, an
adrenal gland problem, liver damage, brain injury,
certain types of poisoning, and some types of kidney diseases. Healthy pregnant
women can have glucose in their urine, which is normal during
pregnancy.

Ketones

Normal: None

Abnormal: Ketones in the
urine can mean uncontrolled diabetes, a very low-carbohydrate diet, starvation
or eating disorders (such as
anorexia nervosa or
bulimia), alcoholism, or poisoning from drinking
rubbing alcohol (isopropanol). Ketones are often found in the urine when a
person does not eat (fasts) for 18 hours or longer. This may occur when a
person is sick and cannot eat or vomits for several days. Low levels of ketones
are sometimes found in the urine of healthy pregnant women.

Microscopic
analysis

Normal: Very few or no red
or white blood cells or casts are seen. No bacteria, yeast cells, parasites, or
squamous cells are present. A few crystals are normally seen.

Abnormal:

Red blood cells in
the urine may be caused by kidney or bladder injury,
kidney stones, a urinary tract infection (UTI),
inflammation of the kidneys (glomerulonephritis), a kidney or
bladder tumor, or systemic lupus erythematosus (SLE). White blood cells (pus)
in the urine may be caused by a urinary tract infection, bladder tumor,
inflammation of the kidneys, systemic lupus erythematosus (SLE), or
inflammation in the vagina or under the foreskin of the penis.

Depending on the type, casts can mean inflammation or damage to the tiny
tubes in the kidneys, poor blood supply to the kidneys, metal poisoning (such
as lead or mercury),
heart failure, or a
bacterial infection.

Large amounts of
crystals, or certain types of crystals, can mean kidney stones, damaged
kidneys, or problems with
metabolism. Some medicines and some types of urinary
tract infections can also increase the number of crystals in urine.

Bacteria in the urine mean a urinary tract infection (UTI). Yeast cells
or parasites (such as the parasite that causes trichomoniasis) can mean an
infection of the urinary tract.

The presence of
squamous cells may mean that the sample is not as pure
as it needs to be. These cells do not mean there is a medical problem, but your
doctor may ask that you give another urine sample.

What To Think About

Bilirubin. This
is a substance formed by the breakdown of red blood cells. It is passed from
the body in stool. Bilirubin is not found in urine. If it is present, it often
means that the liver is damaged or that the flow of bile from the gallbladder is
blocked. To learn more, see the topic
Bilirubin.

Urobilinogen. This is a
substance formed by the breakdown of bilirubin. It is also passed from the body
in stool. Only small amounts of urobilinogen are found in urine. Urobilinogen
in urine can be a sign of liver disease (cirrhosis,
hepatitis) or that the flow of bile from the gallbladder
is blocked.

Bence Jones protein. This is an abnormal protein found
in the urine of about 50% of people with a rare type of cancer called
multiple myeloma. A urine test is often done when
multiple myeloma is suspected. The protein test done during a regular urine
test does not check for Bence Jones protein.

To lower the chance of
contaminating the urine sample with bacteria, a health professional may collect
a urine sample by using a urinary catheter. A catheter may be used to collect
urine from a person in the hospital who is very ill or who can't give a
clean-catch sample. Using a catheter allows a clean sample to be
collected.

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How this information was developed to help you make better health decisions.